/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.druid.frame.processor;

import it.unimi.dsi.fastutil.ints.IntSet;
import org.apache.druid.frame.channel.ReadableFrameChannel;
import org.apache.druid.frame.channel.WritableFrameChannel;

import java.util.Collections;
import java.util.List;

/**
 * Frame processor that simply runs a {@link Runnable}, once.
 */
public class RunnableFrameProcessor implements FrameProcessor<Void>
{
  private final Runnable runnable;

  public RunnableFrameProcessor(Runnable runnable)
  {
    this.runnable = runnable;
  }

  @Override
  public List<ReadableFrameChannel> inputChannels()
  {
    return Collections.emptyList();
  }

  @Override
  public List<WritableFrameChannel> outputChannels()
  {
    return Collections.emptyList();
  }

  @Override
  public ReturnOrAwait<Void> runIncrementally(IntSet readableInputs)
  {
    runnable.run();
    return ReturnOrAwait.returnObject(null);
  }

  @Override
  public void cleanup()
  {
    // Nothing to do.
  }
}
